Physical-chemical studies of a model Ca 2 ion-transport system will be initiated. The objective of this study is to seek quantitative correlations between a number of physical parameters and functional properties of the system, with an ultimate goal of developing a description of the system in structural and thermodynamic terms. The system will be reconstituted from Ca 2 ion-ATPase from the sarcoplasmic reticulumn and single-lamellar phospholipid vesicles. The following properties of the system will be assessed: (1) lipid fluidity, (2) ligand binding properties, (3) ATPase activity, (4) degree of protein aggregation, and (5) Ca 2 ion transport ability. These properties will be monitored using differential scanning calorimetry, reaction calorimetry, rapid kinetic techniques, and fluorescence quenching techniques. Our general hypothesis assumes that the functional properties of the protein (ligand binding, ATPase activity and Ca 2 ion transport) depend upon its structural state (e.g., degree of aggregation) which in turn is modulated by lipid-protein and lipid-lipid interactions. The basic approach will be to perturb (e.g., by temperature, pressure, and anesthetics) the lipid-protein system and quantitatively assess the effect of such perturbations on the system's chemical, physical, and functional properties. The results will be used to develop quantitative relationships between membrane structural fluctuations, protein conformational states and membrane function. The results of this study should aid in the understanding of the function. The results of this study should aid in the understanding of the functioning of membrane systems in general and Ca 2 ion-ATPase in particular.